Glaucoma is a disease of the eye that affects millions of people. Glaucoma is associated with an increase in intraocular pressure resulting either from a failure of a drainage system of an eye to adequately remove aqueous humor from an anterior chamber of the eye or overproduction of aqueous humor by a ciliary body in the eye. Build-up of aqueous humor and resulting intraocular pressure may result in irreversible damage to the optic nerve and the retina, which may lead to irreversible retinal damage and blindness.
Glaucoma may be treated in a number of different ways. One manner of treatment involves delivery of drugs such as beta-blockers or prostaglandins to the eye to either reduce production of aqueous humor or increase flow of aqueous humor from an anterior chamber of the eye. Glaucoma may also be treated by surgical intervention that involves placing a shunt in the eye to result in production of fluid flow pathways between an anterior chamber of an eye and various structures of the eye involved in aqueous humor drainage (e.g., Schlemm's canal, the sclera, or the subconjunctival space). Such fluid flow pathways allow for aqueous humor to exit the anterior chamber.
A problem with implantable shunts is that they are composed of a rigid material, e.g., stainless steel, that does not allow the shunt to react to movement of tissue surrounding the eye. Consequently, existing shunts have a tendency to move after implantation, affecting ability of the shunt to conduct fluid away from the anterior chamber of the eye. To prevent movement of the shunt after implantation, certain shunts are held in place in the eye by an anchor that extends from a body of the shunt and interacts with the surrounding tissue. Such anchors result in irritation and inflammation of the surrounding tissue. Further, implanting a rigid shunt may result in the shunt causing blunt trauma upon insertion into an eye, such as producing a cyclodialysis cleft, or separation of the ciliary body from the scleral spur, creating hypotony by allowing the uncontrolled escape of aqueous humor through the cleft into the suprachoroidal space.
To address the problems associated with shunts made of rigid material, people have begun to make shunts from flexible material, such as gelatin. See for example, Yu et al. (U.S. Pat. No. 6,544,249 and U.S. patent application publication number 2008/0108933). Gelatin shunts may be reactive to pressure, and thus can be implanted without the use of anchors. Consequently, gelatin shunts will maintain fluid flow away for an anterior chamber of the eye after implantation without causing irritation or inflammation to the tissue surrounding the eye. Additionally, the flexibility of a gelatin shunt prevents it from causing blunt trauma upon insertion into an eye, and thus reduces or eliminates the risk of producing a cyclodialysis cleft.
However, there are numerous issues associated with making gelatin shunts. For example, it is difficult to control and manipulate liquid gelatin, which is important in order to produce a gelatin shunt with a uniform cross-section and uniform shape along a length of the implant. Additionally, there are challenges associated with the drying process that also make it difficult to produce a gelatin shunt with a uniform cross-section and uniform shape along a length of the implant.